Routines
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64691: Play Menu Music Tick
Used by the routine at Wait_KeyWithMenuMusic.
One tick of the two-channel menu tune while the key-scan waits. Reads both stream cursors, looks each byte up in Table_MenuMusicDelay, then either bit-bangs the speaker on port 254 (toggling bit 4 via 16) or takes the Continue_MenuMusicTick continue path. Called every pass of Wait_KeyWithMenuMusic_Loop.
Play_MenuMusicTick 64691 LD HL,64647 Point HL at music cursor one (64647).
64694 CALL Read_MusicStreamByte Call Read_MusicStreamByte to read the next stream-one byte.
64697 LD (64644),A Store it at MenuMusic_Workspace.
64700 LD HL,64651 Point HL at music cursor two (64651).
64703 CALL Read_MusicStreamByte Call Read_MusicStreamByte to read the next stream-two byte.
64706 LD (64645),A Store it at 64645.
64709 LD HL,64644 Point HL at stream-one's stored byte (MenuMusic_Workspace).
64712 CALL Decode_MusicDelay Call Decode_MusicDelay to decode its delay pair.
64715 RL E Rotate E left through carry to test the channel flag.
64717 JP C,Continue_MenuMusicTick If carry is set, jump to Continue_MenuMusicTick for the continue path.
64720 PUSH HL Stash the decoded delay on the stack.
64721 LD HL,64645 Point HL at stream-two's stored byte (64645).
64724 CALL Decode_MusicDelay Call Decode_MusicDelay to decode its delay pair.
64727 POP DE Restore stream-one's delay into DE.
64728 LD A,H If stream-one's duration is not 1, jump to Play_MenuMusic_PreparePulse.
64729 DEC A
64730 JR NZ,Play_MenuMusic_PreparePulse
64732 LD A,D If stream-two's duration is 1, jump to Hold_MenuMusicSilence.
64733 DEC A
64734 JR Z,Hold_MenuMusicSilence
Prepare the speaker output value and enter the tone pulse loop.
Play_MenuMusic_PreparePulse 64736 LD A,(64655) Load the delay phase from 64655 into C and clear B.
64739 LD C,A
64740 LD B,0
64742 LD A,(64646) Load the border and speaker bits from 64646.
64745 EX AF,AF' Switch to the alternate accumulator.
64746 LD A,(64646) Reload the border and speaker bits from 64646.
64749 LD IXh,D Keep the inner delay count in IXh.
64751 LD D,16 Load D with 16 (speaker bit mask).
This entry point is used by the routine at Play_MenuMusic_PulseTail.
Inner tone loop: burn delay, write port 254, and toggle the speaker bit.
Play_MenuMusic_PulseLoop 64753 NOP Timing pad before the port write.
64754 NOP
This entry point is used by the routine at Play_MenuMusic_PulseTail.
Write the speaker level and advance the dual delay counters.
Play_MenuMusic_PulseWrite 64755 EX AF,AF' Switch back to the primary accumulator.
64756 DEC E Decrease the fine delay in E.
64757 OUT (254),A Write the border and speaker bits to port 254.
64759 JR NZ,Play_MenuMusic_PulseTail If the fine delay remains, jump to Play_MenuMusic_PulseTail.
64761 LD E,IXh Reload the fine delay from IXh.
64763 XOR D Toggle the speaker bit (16) in A via D.
64764 EX AF,AF' Switch to the alternate accumulator.
64765 DEC L Decrease the coarse delay in L.
64766 JP NZ,Play_MenuMusic_PulseTailWrite If the coarse delay remains, jump to Play_MenuMusic_PulseTailWrite.
This entry point is used by the routine at Play_MenuMusic_PulseTail.
Reload the coarse delay from H and keep pulsing.
Play_MenuMusic_ReloadCoarse 64769 OUT (254),A Write the speaker level to port 254.
64771 LD L,H Copy H into L to reload the coarse delay.
64772 XOR D Toggle the speaker bit (16) in A via D.
64773 DJNZ Play_MenuMusic_PulseLoop Decrease B and loop to Play_MenuMusic_PulseLoop while the outer count remains.
64775 INC C Advance the phase counter in C.
64776 JP NZ,Play_MenuMusic_PulseWrite If the phase remains, jump to Play_MenuMusic_PulseWrite.
64779 RET Return.
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